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Cost Reduction Programs (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Disposition Plant Severance [Member]      
Cost Reduction Initiatives [Abstract]      
Beginning Balance $ 29,000us-gaap_RestructuringReserve
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Incurred 29,000us-gaap_RestructuringAndRelatedCostCostIncurredToDate1
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Settled 0us-gaap_PaymentsForRestructuring
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Adjustments 0us-gaap_RestructuringReserveAccrualAdjustment
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Remaining Balance 29,000us-gaap_RestructuringReserve
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Disposition Plant Severance [Member] | Vertically Integrated Utilities [Member]      
Cost Reduction Initiatives [Abstract]      
Current Period Severance Costs Percentage 68.00%aep_CurrentPeriodSeveranceCostsPercentage
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
/ us-gaap_StatementBusinessSegmentsAxis
= aep_VerticallyIntegratedUtilitiesMember
   
Disposition Plant Severance [Member] | Generation and Marketing [Member]      
Cost Reduction Initiatives [Abstract]      
Current Period Severance Costs Percentage 32.00%aep_CurrentPeriodSeveranceCostsPercentage
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
/ us-gaap_StatementBusinessSegmentsAxis
= aep_GenerationAndMarketingMember
   
Sustainable Cost Reductions [Member]      
Cost Reduction Initiatives [Abstract]      
Severance Costs   7,000us-gaap_SeveranceCosts1
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
47,000us-gaap_SeveranceCosts1
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
Appalachian Power Co [Member] | Disposition Plant Severance [Member]      
Cost Reduction Initiatives [Abstract]      
Beginning Balance 9,304us-gaap_RestructuringReserve
/ dei_LegalEntityAxis
= aep_AppalachianPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Expense Allocation from AEPSC 292aep_ExpenseAllocationFromAepsc
/ dei_LegalEntityAxis
= aep_AppalachianPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Incurred 6,820us-gaap_RestructuringAndRelatedCostCostIncurredToDate1
/ dei_LegalEntityAxis
= aep_AppalachianPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Settled (2,192)us-gaap_PaymentsForRestructuring
/ dei_LegalEntityAxis
= aep_AppalachianPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
[1]    
Adjustments 0us-gaap_RestructuringReserveAccrualAdjustment
/ dei_LegalEntityAxis
= aep_AppalachianPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Remaining Balance 9,304us-gaap_RestructuringReserve
/ dei_LegalEntityAxis
= aep_AppalachianPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Appalachian Power Co [Member] | Sustainable Cost Reductions [Member]      
Cost Reduction Initiatives [Abstract]      
Severance Costs   275us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= aep_AppalachianPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
8,472us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= aep_AppalachianPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
Indiana Michigan Power Co [Member] | Disposition Plant Severance [Member]      
Cost Reduction Initiatives [Abstract]      
Beginning Balance 8,023us-gaap_RestructuringReserve
/ dei_LegalEntityAxis
= aep_IndianaMichiganPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Expense Allocation from AEPSC 162aep_ExpenseAllocationFromAepsc
/ dei_LegalEntityAxis
= aep_IndianaMichiganPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Incurred 8,023us-gaap_RestructuringAndRelatedCostCostIncurredToDate1
/ dei_LegalEntityAxis
= aep_IndianaMichiganPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Settled 162us-gaap_PaymentsForRestructuring
/ dei_LegalEntityAxis
= aep_IndianaMichiganPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Adjustments 0us-gaap_RestructuringReserveAccrualAdjustment
/ dei_LegalEntityAxis
= aep_IndianaMichiganPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Remaining Balance 8,023us-gaap_RestructuringReserve
/ dei_LegalEntityAxis
= aep_IndianaMichiganPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Indiana Michigan Power Co [Member] | Sustainable Cost Reductions [Member]      
Cost Reduction Initiatives [Abstract]      
Severance Costs   355us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= aep_IndianaMichiganPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
5,678us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= aep_IndianaMichiganPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
Ohio Power Co [Member] | Disposition Plant Severance [Member]      
Cost Reduction Initiatives [Abstract]      
Beginning Balance 0us-gaap_RestructuringReserve
/ dei_LegalEntityAxis
= aep_OhioPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Expense Allocation from AEPSC 80aep_ExpenseAllocationFromAepsc
/ dei_LegalEntityAxis
= aep_OhioPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Incurred 0us-gaap_RestructuringAndRelatedCostCostIncurredToDate1
/ dei_LegalEntityAxis
= aep_OhioPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Settled 80us-gaap_PaymentsForRestructuring
/ dei_LegalEntityAxis
= aep_OhioPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Adjustments 0us-gaap_RestructuringReserveAccrualAdjustment
/ dei_LegalEntityAxis
= aep_OhioPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Remaining Balance 0us-gaap_RestructuringReserve
/ dei_LegalEntityAxis
= aep_OhioPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Ohio Power Co [Member] | Sustainable Cost Reductions [Member]      
Cost Reduction Initiatives [Abstract]      
Severance Costs   5,831us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= aep_OhioPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
13,498us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= aep_OhioPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
Public Service Co Of Oklahoma [Member] | Disposition Plant Severance [Member]      
Cost Reduction Initiatives [Abstract]      
Beginning Balance 134us-gaap_RestructuringReserve
/ dei_LegalEntityAxis
= aep_PublicServiceCoOfOklahomaMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Expense Allocation from AEPSC 154aep_ExpenseAllocationFromAepsc
/ dei_LegalEntityAxis
= aep_PublicServiceCoOfOklahomaMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Incurred 134us-gaap_RestructuringAndRelatedCostCostIncurredToDate1
/ dei_LegalEntityAxis
= aep_PublicServiceCoOfOklahomaMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Settled 154us-gaap_PaymentsForRestructuring
/ dei_LegalEntityAxis
= aep_PublicServiceCoOfOklahomaMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Adjustments 0us-gaap_RestructuringReserveAccrualAdjustment
/ dei_LegalEntityAxis
= aep_PublicServiceCoOfOklahomaMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Remaining Balance 134us-gaap_RestructuringReserve
/ dei_LegalEntityAxis
= aep_PublicServiceCoOfOklahomaMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Public Service Co Of Oklahoma [Member] | Sustainable Cost Reductions [Member]      
Cost Reduction Initiatives [Abstract]      
Severance Costs   (147)us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= aep_PublicServiceCoOfOklahomaMember
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
3,675us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= aep_PublicServiceCoOfOklahomaMember
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
Southwestern Electric Power Co [Member] | Disposition Plant Severance [Member]      
Cost Reduction Initiatives [Abstract]      
Beginning Balance 84us-gaap_RestructuringReserve
/ dei_LegalEntityAxis
= aep_SouthwesternElectricPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Expense Allocation from AEPSC 205aep_ExpenseAllocationFromAepsc
/ dei_LegalEntityAxis
= aep_SouthwesternElectricPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Incurred 84us-gaap_RestructuringAndRelatedCostCostIncurredToDate1
/ dei_LegalEntityAxis
= aep_SouthwesternElectricPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Settled 205us-gaap_PaymentsForRestructuring
/ dei_LegalEntityAxis
= aep_SouthwesternElectricPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Adjustments 0us-gaap_RestructuringReserveAccrualAdjustment
/ dei_LegalEntityAxis
= aep_SouthwesternElectricPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Remaining Balance 84us-gaap_RestructuringReserve
/ dei_LegalEntityAxis
= aep_SouthwesternElectricPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_CostReductionInitiativeMember
   
Southwestern Electric Power Co [Member] | Sustainable Cost Reductions [Member]      
Cost Reduction Initiatives [Abstract]      
Severance Costs   $ 1,017us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= aep_SouthwesternElectricPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
$ 5,709us-gaap_SeveranceCosts1
/ dei_LegalEntityAxis
= aep_SouthwesternElectricPowerCoMember
/ us-gaap_RestructuringPlanAxis
= aep_SustainableCostReductionsMember
[1] Settled includes amounts received from affiliates for expenses related to joint plant.